The neuropeptide receptors for Neurokinin 1 (substance P, NK-1) are widely distributed throughout the mammalian nervous system (especially brain and spinal ganglia), the circulatory system and peripheral tissues (especially the duodenum and jejunum) and are involved in regulating a number of diverse biological processes. Substance P is a naturally occurring undecapeptide belonging to the tachykinin family of peptides, the latter being so-named because of their prompt contractile action on extravascular smooth muscle tissue. The receptor for substance P is a member of the superfamily of G protein-coupled receptors.
The central and peripheral actions of the mammalian tachykinin, substance P, have been associated with numerous inflammatory conditions including migraine, rheumatoid arthritis, asthma, and inflammatory bowel disease as well as mediation of the emetic reflex and the modulation of central nervous system (CNS) disorders such as Parkinson""s disease (Neurosci. Res., 1996, 7, 187-214) anxiety (Can. J. Phys., 1997, 75, 612-621) and depression (Science, 1998, 281, 1640-1645).
Evidence for the usefulness of tachykinin receptor antagonists in pain, headache, especially migraine, Alzheimer""s disease, multiple sclerosis, attenuation of morphine withdrawal, cardiovascular changes, oedema, such as oedema caused by thermal injury, chronic inflammatory diseases such as rheumatoid arthritis, asthma/bronchial hyperreactivity and other respiratory diseases including allergic rhinitis, inflammatory diseases of the gut including ulcerative colitis and Crohn""s disease, ocular injury and ocular inflammatory diseases is reviewed in xe2x80x9cTachykinin Receptor and Tachykinin Receptor Antagonistsxe2x80x9d, J. Auton. Pharmacol., 13, 23-93, 1993.
Furthermore, Neurokinin 1 receptor antagonists are being developed for the treatment of a number of physiological disorders associated with an excess or imbalance of tachykinin, in particular substance P. Examples of conditions in which substance P has been implicated include disorders of the central nervous system such as anxiety, depression and psychosis (WO 95/16679, WO 95/18124 and WO 95/23798).
The neurokinin-1-receptor antagonists are further useful for the treatment of motion sickness and for treament induced vomiting.
In addition, in The New England Journal of Medicine, Vol. 340, No.3 190-195, 1999 has been described the reduction of cisplatin-induced emesis by a selective neurokinin-1-receptor antagonist.
Furthermore, U.S. Pat. No. 5,972,938 describes a method for treating a psychoimmunologic or a psychosomatic disorder by administration of a tachykinin receptor, such as NK-1 receptor antagonist.
In accordance with the present invention, the compounds of formula I and their salts are characterized by valuable therapeutic properties. It has been surprisingly found that the compounds of the present invention are antagonists of the Neurokinin 1 (NK-1, substance P) receptor.
Objects of the present invention are the compounds of formula I and pharmaceutically acceptable salts thereof, the preparation of the above-mentioned compounds, medicaments containing them and their manufacture as well as the use of the above-mentioned compounds in the control or prevention of illnesses, especially of illnesses and disorders of the kind referred to earlier or in the manufacture of corresponding medicaments.
The most preferred indications in accordance with the present invention are those, which include disorders of the central nervous system, for example the treatment or prevention of certain depressive disorders or emesis by the administration of NK-1 receptor antagonists. A major depressive episode has been defined as being a period of at least two weeks during which, for most of the day and nearly every day, there is either depressed mood or the loss of interest or pleasure in all, or nearly all activities.
The present invention relates to compounds of the formula: 
wherein
R is hydrogen, lower alkyl, lower alkoxy, halogen, amino, xe2x80x94N(R6)2 or trifluoromethyl;
R1 is hydrogen, lower alkoxy or halogen;
R and R1 may be together xe2x80x94CHxe2x95x90CHxe2x80x94CHxe2x95x90CHxe2x80x94;
R2 is halogen, lower alkyl or trifluoromethyl;
R3 is hydrogen or lower alkyl;
R4 is hydrogen or a cyclic tertiary amine, optionally substituted by lower alkyl;
R5 is hydrogen, nitro, amino or xe2x80x94N(R6)2;
R6 is hydrogen or lower alkyl;
X is xe2x80x94C(O)N(R6)xe2x80x94, xe2x80x94(CH2)nOxe2x80x94, xe2x80x94(CH2)nN(R6)xe2x80x94, xe2x80x94N(R6)C(O)xe2x80x94 or xe2x80x94N(R6)(CH2)nxe2x80x94; and
n is 1-2;
and to pharmaceutically acceptable acid addition salts thereof.
The following definitions of the general terms used in the present description apply irrespective of whether the terms in question appear alone or in combination.
As used herein, the term xe2x80x9clower alkylxe2x80x9d denotes a straight- or branched-chain alkyl group containing from 1-7 carbon atoms, for example, methyl, ethyl, propyl, isopropyl, n-butyl, i-butyl, t-butyl and the like.
Preferred lower alkyl groups are groups with 1-4 carbon atoms.
The term xe2x80x9clower alkoxyxe2x80x9d denotes a group wherein the alkyl residues are as defined above, and which is attached via an oxygen atom.
The term xe2x80x9chalogenxe2x80x9d denotes chlorine, iodine, fluorine and bromine.
The term xe2x80x9ccycloalkylxe2x80x9d denotes a saturated carbocyclic group, containing 3-6 carbon atoms.
The term xe2x80x9ccyclic tertiary aminexe2x80x9d denotes, for example, pyrrol-1-yl, imidazol-1-yl, piperidin-1-yl, piperazin-1-yl, morpholin-4-yl, thiomorpholin-4-yl, 1-oxo-thiomorpholin-4-yl or 1,1-dioxo-thiomorpholin-4-yl. Preferred is the piperazine group.
The term xe2x80x9cpharmaceutically acceptable acid addition saltsxe2x80x9d embraces salts with inorganic and organic acids, such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, citric acid, formic acid, fumaric acid, maleic acid, acetic acid, succinic acid, tartaric acid, methane-sulfonic acid, p-toluenesulfonic acid and the like.
Exemplary preferred are compounds, in which X is xe2x80x94C(O)N(R6)xe2x80x94, wherein R6 is methyl, for example the following compounds:
2xe2x80x2-methyl-biphenyl-2-carboxylic acid-(3,5-bis-trifluoromethyl-benzyl)-methyl-amide,
2xe2x80x2-methyl-5-(4-methyl-piperazin-1-yl)-biphenyl-2-carboxylic acid-(3,5-bis-trifluoromethyl-benzyl)-methyl-amide and
2xe2x80x2-chloro-5-(4-methyl-piperazin-1-yl)-biphenyl-2-carboxylic acid-(3,5-bis-trifluoromethyl-benzyl)-methyl-amide.
Further preferred are compounds, in which X is xe2x80x94N(R6)xe2x80x94COxe2x80x94, wherein R6 is methyl.
Examples of such compounds are:
2-(3,5-bis-trifluoromethyl-phenyl)-N-methyl-N-(2xe2x80x2-methyl-4-nitro-biphenyl-2-yl)-isobutyramide,
N-(4-amino-2xe2x80x2-methyl-biphenyl-2-yl)-2-(3,5-bis-trifluoromethyl-phenyl)-N-methyl-isobutyramide,
2-(3,5-bis-trifluoromethyl-phenyl)-N-methyl-N-(2xe2x80x2-methyl-4-methylamino-biphenyl-2-yl)-isobutyramide,
2-(3,5-bis-trifluoromethyl-phenyl)-N-methyl-N-(2xe2x80x2-methyl-biphenyl-2-yl)-isobutyramide and
N-(2xe2x80x2-amino-biphenyl-2-yl)-2-(3,5-bis-trifluoromethyl-phenyl)-N-methyl-isobutyramide.
The present compounds of formula I and their pharmaceutically acceptable salts can be prepared by methods known in the art, for example, by processes described below, which process comprises
a) reacting a compound of formula: 
xe2x80x83with a compound of formula: 
xe2x80x83to a compound of formula: 
wherein R1-R6, R and n have the significances given above, or
b) reacting a compound of formula: 
xe2x80x83with a compound of formula: 
xe2x80x83to give a compound of formula: 
wherein R1-R6, R and n have the significances given above, or
c) reducing a compound of formula: 
xe2x80x83to a compound of formula: 
wherein the definitions of substituents are given above, or
d) reacting a compound of formula: 
xe2x80x83with a compound of formula: 
xe2x80x83to a compound of formula: 
wherein the definitions of substituents are given above, or
e) reacting a compound of formula: 
xe2x80x83with a compound of formula: 
xe2x80x83to a compound of formula: 
wherein the definitions of substituents are given above, or
i) reducing a compound of formula: 
xe2x80x83to a compound of formula: 
wherein the definitions of substituents are given above, or
g) reacting a compound of formula: 
xe2x80x83with a compound of formula: 
xe2x80x83to a compound of formula: 
wherein the definitions of substituents are given above, or
h) methylating a compound of formula: 
xe2x80x83to a compound of formula: 
wherein the substituents are given above, or
i) reacting a compound of formula: 
xe2x80x83with a compound of formula: 
xe2x80x83to a compound of formula: 
wherein the definition of substituents is given above, or
j) modifying one or more substituents R1-R6 or R within the definitions given above, and if desired, converting the compound obtained into a pharmaceutically acceptable acid addition salt.
In accordance with process variant a) to a cooled solution of a compound of formula II, for example 2xe2x80x2-methyl-4-nitro-biphenyl-2-amine and DIPEA (N-ethyldiisopropyl-amine) is added a solution of a compound of formula III, for example 2-(3,5-bis-trifluoromethyl-phenyl)-2-methyl-propionyl chloride in dichloromethane and the mixture is stirred at temperatures between 35-40xc2x0 C. The desired compound of formula I-1 is yielded after purification in good yields.
Process variant b) describes the reaction of a compound of formula IV with a compound of formula V to a compound of formula I-2. The reaction is carried out in conventional manner, for example in a solvent, such as toluene and in presence of triethyl-amine. The mixture is refluxed for about 1 hour.
In accordance with process variant c) a compound of formula I-2 is reduced to a compound of formula I-4. This reaction is carried out with a reducing agent, such as LiAlH4 or BH3.THF, in conventional manner.
Process variant d) describes the reaction of a compound of formula VI with a compound of formula VII to a compound of formula I-2. This reaction is carried out by deprotonation of a compound of formula VI with KHMDS (potassium hexamethyldisilazide) and subsequent addition of a compound of formula VII. A suitable solvent is tetrahydrofuran. The reaction is carried out at room temperature.
In accordance with process variant e) a compound of formula I-5 is prepared. This reaction is carried out by deprotonation of a compound of formula VIII with NaH and subsequent addition of a compound of formula VII. This reaction is carried out in conventional manner.
A further method for the preparation of a compound of formula I is described in process variant f). A compound of formula I-1 is reduced to a compound of formula I-3 in conventional manner, for example with LiAlH4 or BH3.THF.
In accordance with variant g) a compound of formula XII is reacting with a compound of formula XIII to give a compound of formula I-5. This reaction is carried out in conventional manner with NaH in the presence of a solvent, such as DMF.
Reaction variant h) describes the methylation of a compound of formula I-41 with formaline and NaBH4 to a compound of formula I-42.
Process variant i) describes the process for preparation of a compound of formula I-1, wherein a compound of formula XIII is activating with CDI and subsequent addition of a compound of formula II yields a compound of formula I-1.
The salt formation is effected at room temperature in accordance with methods which are known per se and which are familiar to any person skilled in the art. Not only salts with inorganic acids, but also salts with organic acids came into consideration. Hydrochlorides, hydrobromides, sulphates, nitrates, citrates, acetates, maleates, succinates, methan-sulphonates, p-toluenesulphonates and the like are examples of such salts.
The following schemes 1-5 describe the processes for preparation of compounds of formula I in more detail. The starting materials of formulae II, III, IX, X, XI, XII, XIII, XIV and XV are known compounds and may be prepared according to methods known in the art.
In the schemes the following abbreviations have been used:

The substituents are given above. 
The definition of substituents is given above. 
The definition of substituents is given above. 
The definition of substituents is given above. 
The definition of substituents is given above. 
The definition of substituents is given above. 
The definition of substituents is given above.
As mentioned earlier, the compounds of formula I and their pharmaceutically usable addition salts possess valuable pharmacological properties. It has been found that the compounds of the present invention are antagonists of the Neurokinin 1 (NK-1, substance P) receptor.
The compounds were investigated in accordance with the tests given hereinafter.
The affinity of test compounds for the NK-1 receptor was evaluated at human NK-1 receptors in CHO cells infected with the human NK-1 receptor (using the Semliki virus expression system) and radiolabelled with [3H] substance P (final concentration 0.6 nM). Binding assays were performed in HEPES buffer (50 mM, pH 7.4) containing BSA (0.04%) leupeptin (8 xcexcg/ml), MnCl2 (3 mM) and phosphoramidon (2 xcexcM). Binding assays consisted of 250 xcexcl of membrane suspension (1.25xc3x97105 cells/assay tube), 0.125 xcexcl of buffer of displacing agent and 125 xcexcl of [3H] substance P. Displacement curves were determined with at least seven concentrations of the compound. The assay tubes were incubated for 60 min at room temperature after which time the tube contents were rapidly filtered under vacuum through GF/C filters presoaked for 60 min with PEI (0.3%) with 2xc3x972 ml washed of HEPES buffer (50 mM, pH 7.4). The radioactivity retained on the filters was measured by scintillation counting. All assays were performed in triplicate in at least 2 separate experiments.
The affinity to the NK-1 receptor, given as pKi, is in the scope of 8.00-9.00 for the preferred compounds. Examples of such compounds are:
The compounds of formula I as well as their pharmaceutically usable acid addition salts can be used as medicaments, e.g. in the form of pharmaceutical preparations. The pharmaceutical preparations can be administered orally, e.g. in the form of tablets, coated tablets, dragxc3xa9es, hard and soft gelatine capsules, solutions, emulsions or suspensions. The administration can, however, also be effected rectally, e.g. in the form of suppositories, or parenterally, e.g. in the form of injection solutions.
The compounds of formula I and their pharmaceutically usable acid addition salts can be processed with pharmaceutically inert, inorganic or organic excipients for the production of tablets, coated tablets, dragxc3xa9es and hard gelatine capsules. Lactose, corn starch or derivatives thereof, talc, stearic acid or its salts etc can be used as such excipients e.g. for tablets, dragxc3xa9es and hard gelatine capsules.
Suitable excipients for soft gelatine capsules are e.g. vegetable oils, waxes, fats, semi-solid and liquid polyols etc.
Suitable excipients for the manufacture of solutions and syrups are e.g. water, polyols, saccharose, invert sugar, glucose etc.
Suitable excipients for injection solutions are e.g. water, alcohols, polyols, glycerol, vegetable oils etc.
Suitable excipients for suppositories are e.g. natural or hardened oils, waxes, fats, semi-liquid or liquid polyols etc.
Moreover, the pharmaceutical preparations can contain preservatives, solubilizers, stabilizers, wetting agents, emulsifiers, sweeteners, colorants, flavorants, salts for varying the osmotic pressure, buffers, masking agents or antioxidants. They can also contain still other therapeutically valuable substances.
The dosage can vary within wide limits and will, of course, be fitted to the individual requirements in each particular case. In general, in the case of oral administration a daily dosage of about 10 to 1000 mg per person of a compound of formula I should be appropriate, although the above upper limit can also be exceeded when necessary.